Index head in semiconductor device test handler

ABSTRACT

An index head assembly for a semiconductor device test handler is provided which allows for precise positioning of a device in a test socket, as well as accurate testing of the device once properly positioned in the test socket. The head portion of the index head assembly includes a holding part which absorbs and holds the device using a vacuum force, a heating part which generates heat to maintain the device at the appropriate temperature, and a compliance part which accurately aligns and positions the index head relative to the test socket so that the device may be properly connected to the test socket. The downward force used to connect the semiconductor device to the test socket is controlled by a force transducer, and the temperature of the semiconductor device is accurately controlled through direct heat transfer from an electric heater provided within the head portion of the index head assembly. A plurality of ball plungers and guide members, as well as the particular installation of various parts of the head portion relative to one another ensure proper alignment of the device within the test socket.

This application claims the benefit of the Korean Application No.P2001-1118 filed on Jan. 9, 2001, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an index head in a semiconductor devicetest handler, and more particularly, to an index head in a semiconductordevice test handler for mounting semiconductor device in a test socketat a test site.

Background of the Related Art

In general, modular ICs, in which memory, and/or non-memorysemiconductor devices are fabricated on one substrate appropriately incircuit basis, are main components that serve important functions incomputers or home appliances, which are shipped after various testing.As known, the handler is equipment required for automatic testing of thesemiconductor device and modular RAM.

In general, many of the handlers are designed to carry out, not only ageneral performance tests under a room temperature, but also hightemperature tests, and low temperature tests in which the semiconductordevices, the modular ICs, and the like are tested if they are operativenormally under an extremely high temperature, or low temperatureenvironment formed by using electric heater or liquefied nitrogenspraying system into a enclosed chamber at the test site.

In the meantime, the index head in the handler serves holdingsemiconductor devices in the test site under such an extremely high orlow temperature, and mounting/dismounting to/from test sockets, as wellas pressing down the semiconductor devices in a state the semiconductordevices are mounted in the test sockets for reducing contact resistancesbetween the sockets and leads on the semiconductor devices.

The index head also serves to prevent a temperature drop of thesemiconductor devices in the sockets during temperature testing byblowing hot air to the semiconductor devices in a state the index headpresses down the semiconductor devices. However, the foregoing relatedart index head has the following problems.

First, in the hot air blowing for prevention of the temperature drop ofthe semiconductor devices, an accurate temperature control has beendifficult, and even parts that require no heating are heated.

Second, the related art index head is provided with a compliancemechanism (or a floating mechanism) for an exact alignment between theheld semiconductor devices and the sockets, which becomes shaky in highspeed operation of the index head, that limits an operation speed of theindex head.

Third, because a pressing down force of the index head on thesemiconductors in the sockets influences a result of the test, it isrequired to control and monitor the pressing down force. However, therelated art index head is not provided with devices for automaticcontrol and monitoring the pressing down force, such that a worker isrequired to make sure and adjust the force, personally. Accordingly, anaccurate control of the force has been difficult, and if the force isexcessive, the semiconductor devices are damaged.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an index head in asemiconductor device test handler that substantially obviates one ormore of the problems due to limitations and disadvantages of the relatedart.

An object of the present invention is to provide an index head in asemiconductor device test handler, which permits an accurate temperaturecontrol, a stable operation of the compliance mechanism, and anautomatic accurate control of a pressing down force.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, the indexhead in a semiconductor device test handler, for holding semiconductordevices, and mounting/dismounting to/from test sockets, includes acarrier base fixedly fitted to a transfer device movable in anydirection, an elevating carrier coupled to the carrier base to bemovable in up and down directions, elevating means for moving theelevating carrier in up and down directions with respect to the carrierbase, a head holder under the elevating carrier coupled to the elevatingcarrier via a guide member for making relative movement with respect tothe elevating carrier in up and down directions, and a plurality ofheads each including a holding part fixedly fitted to a bottom of thehead holder for holding the semiconductor device by vacuum, a heatingpart on top of the holding part for transfer of a heat to thesemiconductor device directly when the semiconductor device is mountedin the test socket, and a compliance part fitted over the heating partfor providing degrees of freedom for an alignment between thesemiconductor device held by the holding part and the test socket.

The index head further includes a force transducer between the elevatingcarrier and the head holder for automatic measurement of a load appliedby the elevating carrier in proportion to displacement of the elevatingcarrier with respect to the head holder when the semiconductor devicemounted in the test socket is pressed down.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention:

In the drawings:

FIG. 1 illustrates a perspective view of an index head in accordancewith a preferred embodiment of the present invention;

FIGS. 2A and 2B illustrate side sections of key parts of the index headin FIG. 1, each showing a system and operation of the index head;

FIG. 3 illustrates a perspective view of a head holder part of the indexhead of the present invention;

FIG. 4 illustrates a flow chart of control of the index head operationby using the load cell in FIG. 2A;

FIG. 5 illustrates a disassembled perspective view of a head part of theindex head in FIG. 1;

FIG. 6 illustrates a perspective view of a bottom of a holding part inthe head part in FIG. 5;

FIG. 7 illustrates a longitudinal section of key parts of disassembledhead part in FIG. 5;

FIGS. 8A-8D explain an operation principle of the compliance part in thehead part in FIG. 6, wherein,

FIG. 8A illustrates a state in which an alignment is made by thecompliance part;

FIG. 8B illustrates an operation principle of the compliance part in astate an offset is occurred;

FIG. 8C illustrates an operation principle of the compliance part in astate a tilting is occurred; and,

FIG. 8D illustrates an operation principle of the compliance part in astate a rotation is occurred.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. FIGS. 1, and 2A and 2B illustrate an entire system andoperation an index head in accordance with a preferred embodiment of thepresent invention.

Referring to the drawings, the index head includes a carrier base 10fitted to a transfer device (not shown) movable in X-Y-Z directionsand/or a ‘θ’ direction, a rotation direction, within a test site (notshown), an elevating carrier 20 coupled to the carrier base 10 with anLM guide 11 in between, a ball screw 13 fitted to the carrier base 10 tobe coupled to the elevating carrier 20 for transmission of an up/downdriving force to the elevating carrier 20, and a servo motor 12 fordriving the ball screw 13.

There is a head holder 30 under the elevating carrier 20 coupled theretovia an LM guide 21 for making relative movement with respect to theelevating carrier 20, and there are a plurality of heads 40 under thehead holder 30 fixedly coupled thereto for holding the semiconductordevices 1 by vacuum and mounting/dismounting to/from the test sockets 2.

There is a load cell 35 in a central part of a top of the head holder 30as a force transducer for measuring a load applied to the elevatingcarrier 20 in proportion to a displacement of the elevating carrier 20with respect to the head holder 30 when the head 40 mounts thesemiconductor device 1 to the test socket 2 and applies a pressurethereto, thereby controlling operation of the servo motor 12.

Accordingly, referring to FIG. 4, if the elevating carrier 20 moves downwith respect to the head holder 30 in a state the index head 40 of thepresent invention mounts the semiconductor devices 1 to the test sockets2, the load is measured in proportion to a degree of compression as theload cell 35 is compressed by the downward movement of the elevatingcarrier 20. When the load applied to the load cell 35 reaches to apreset point, i.e., to an appropriate load, a control part (not shown)which controls operation of the servo motor 12 senses it, and stopsoperation of the servo motor 12, under which condition the test of thesemiconductor device is carried out.

By the way, referring to FIG. 3, the head holder 130 may be providedwith one pair of guide pins 131 fitted on both sides of a top partthereof to couple with coupling holes correspondingly formed in theelevating carrier 20, thereby coupling the head holder 130 to theelevating carrier 20.

In the meantime, with regard the head structures illustrated in FIGS. 2Aand 2B, the head 40 includes a holding part 41 fixedly fitted to abottom of the head holder 30 for holding the semiconductor device byvacuum, a heating part 42 on top of the holding part 41 for transfer ofa heat to the semiconductor device directly when the semiconductordevice is mounted in the test socket 2, and a compliance part 43 fittedover the heating part 42 spaced therefrom for providing degrees offreedom for an alignment between the semiconductor device held by theholding part 41 and the test socket 2.

The holding part 41 in the head 40 includes a pocket block 411 of aconductive material with a good heat conductivity having a through hole412 in a center for close contact coupling with the heating part 42, afloating nozzle 413 inserted in the through hole 412 in the pocket block411 for holding the semiconductor device by vacuum, and a plurality ofblades 415 of a non-conductive material vertical to a bottom surface ofthe pocket block for pressing leads of the semiconductor device heldunder the floating nozzle 413 to contact with terminal part (not shown)of the test socket 2.

The floating nozzle 413 in the holding part 41 is designed to allow afree movement in up/down directions for a distance within the throughhole 412, by forming steps at an upper part and a lower part of thethrough hole 412 respectively to have diameters greater than anintermediate part thereof, coupling a nut 414 to an upper part of thefloating nozzle 413 in a state the floating nozzle 413 is passed throughthe through hole 412, and forming an annular rim 413 a on a lower partof the floating nozzle 413, to form a gap between the lower part step ofthe through hole 412 and the rim 413 a of the floating nozzle 413 whenthe floating nozzle 413 is set on the through hole 412 by gravity,thereby allowing the free movement in up/down directions for a distancewithin the through hole 412 as much as the gap.

Accordingly, when the head 40 presses down the semiconductor devicemounted in the socket 2 (see FIG. 1), a top surface of the semiconductordevice is brought into contact with the bottom surface of the pocketblock 411 as the floating nozzle 413 move upward.

There are positioning holes 416 in opposite side parts of the pocketblock 411 in correspondence to, and to be inserted and passed throughpositioning pins 2 a (see FIG. 8A) in the vicinity of the test socket 2for accurate guidance of the head 40 to the test socket in a process thehead 40 holds the semiconductor device and mounts in the test socket 2,wherein each of the positioning pins 2 a on the test socket 2 has aconical peak for easy insertion of the head 40 even if there is a slightmisalignment between the head 40 and the socket 2, for alignment betweenthe head 40 and the test socket 2, together with the compliance part 43explained, later.

In the meantime, the heating part 42 in the head 40 includes a heatingblock 421 on top of the holding part 41 having a built-in electricheater 422 for transfer of a heat to the pocket block 411, a throughhole 426 in a central part of the heating block 421, and a couplingnozzle 423 passed through, and fixed to the through hole 426.

A lower end of the coupling nozzle 423 is fixed to a top end of thefloating nozzle 413 in the holding part 41, and is formed of flexiblesilicone for free upward movement of the floating nozzle 413.

The heating block 421 has coupling bosses 425 at four corners of the toppart for coupling with the compliance part 43. The coupling bosses 425are formed of an insulating material for cutting off heat transfer fromthe heating block 421 to the compliance part 43.

In the meantime, the compliance part 43 includes a lower block 435 fixedto the heating part 42, and an upper block 431 coupled to the lowerblock 435 with allowances for having degrees of freedom in X-Y-Z androtation θ directions.

There are a plurality of holes 433 for receiving ball plungers 434,compression springs 434 a, retainers 434 b fitted to lower ends of thecompression springs 434 a, and balls 434 c retained under the retainers434 b and exposed outside of the bottom surface of the upper block 431.

The lower block 435 has ball buttons 437 of conical recess at positionscorresponding to the holes 433 in the upper block 431 for receiving theballs 434 c in the ball plungers 434.

There is a coupling hole 432 or 436 in each central part of the upperblock 431 and the lower block 435, for coupling with the coupling nozzle423, and there is an O-ring 439 between the upper block 431 and thelower block 435 for improvement of air tightness at a contact part ofthe two coupling holes 432 and 436.

In the meantime, a top part of the coupling hole 432 in the upper block431 is connected to an external air pump (not shown) for evacuation.

The operation of the compliance part 43 will be explained with referenceto FIGS. 8A-8D.

FIG. 8A illustrates a state in which an alignment between the head 40and the test socket 2 is made by the compliance part 43, to mount thesemiconductor device 1 in the test socket 2, wherein, when the holdingpart 41 in the head 40 moves down onto the test socket 2 in a state theholding part 41 holds the semiconductor device 1, the head 40 is guidedto the test socket 2 to mount the semiconductor device 1 in the socket 2as the positioning pins 2 a on the test socket 2 are inserted into thepositioning holes 416 in the pocket block 411 of the head 40.

If there is an alignment error between the head 40 and the test socket 2caused by tolerances in assembly, or fabrication of the index headand/or the test socket, the alignment error is corrected in a processthe positioning pins 2 a are inserted into the pocket block 411 in thehead 40 because the upper block 431 and the lower block 435 in thecompliance part 43 has coupled with degrees of freedom in X-Y-Z androtation θ directions.

That is, referring to FIGS. 8B, 8C, and 8D, if there is the alignmenterror, such as offset error, tilting error, or rotation error, betweenthe head 40 and the test socket 2, a position is corrected by a relativepositional movement between the lower block 435 and the upper block 431in the compliance part 43 in a process the positioning pins 416 areinserted into the positioning holes 416 in the head 40 when the head 40moves down toward the test socket 2.

Of course, a limit of the alignment error correction by the compliancepart 43 is within a range the positioning holes 416 move down by gravityguided by the conical parts at top ends of the positioning pins 2 a whenthe head 40 moves down. The operation of the foregoing index head willbe explained.

When a test tray or a carrier containing semiconductor devices to betested comes to a test site of the handler, the holding part 41 in thehead 40 of the index head holds the semiconductor device and moves to aposition right upper side of the test socket 2.

Thus, when the index head comes to the upper side of the test socket 2,the servo motor 12 on the carrier base 10 comes into operation to movedown the elevating carrier 20 along the LM guide 11, until thesemiconductor device 1 is mounted in the test socket 2 as thepositioning holes 416 in the head 40 are inserted into the positioningpins 2 a at the test socket 2.

As explained, even if there is an alignment error between the head 40and the test socket 2 caused by tolerances in assembly, or fabricationof the index head and/or the test socket, the semiconductor device canbe mounted in the test socket 2 accurately as the alignment between thehead 40 and the test socket 2 is made by the compliance part 43 in thehead 40.

In this instance, as the floating nozzle 413 in the holding part 41 inthe head 40 that holds the semiconductor device moves upward on the sametime the semiconductor device 1 is mounted in the test socket 2, tobring a top surface of the semiconductor device 1 to come into contactwith the bottom surface of the pocket block 411.

If the servo motor 12 moves down the elevating carrier 20 further in astate the semiconductor device 1 is mounted in the socket 2, theelevating carrier 20 moves down with respect to the head holder 30, topress down the semiconductor device 1, when, as explained, the elevatingcarrier 20 presses down the load cell 35 in proportion to the downwardmovement of the elevating carrier 20 with respect to the head holder 30until the load on the load cell 35 reaches to a preset point, whenoperation of the servo motor 12 is stopped, and the test is started.

When the test is started in this state, the electric heater 422 in theheating part 42 is put into operation to heat the heating block 421, theheat is transferred to the pocket block 411, and to the semiconductordevice 1 in contact with the pocket block 411 continuously, therebypreventing temperature drop of the semiconductor device.

When the test of the semiconductor device is finished at the test socket2, the semiconductor device is dismounted from the test socket 2 in aprocess reverse of the foregoing mounting process, and placed in anempty tray or carrier.

As has been explained, the index head in a semiconductor device testhandler of the present invention has the following advantages.

The accurate control of the force applied to the semiconductor devicemay means of the force transducer fitted to the head holder improves atest reliability and permits an easy adjustment of the applied force.

The direct transfer of a heat to the semiconductor device, withoutblowing hot air thereto the same as the related art, for prevention oftemperature drop of the semiconductor device permits an easy andaccurate temperature control, and protect other parts of the equipmentthat require no temperature drop prevention.

Along with this, the smooth alignment between the index head and/or thetest socket by the compliance part permits to progress the test fasterthan before because the index head has a small vibration even in highspeed operation of the index head.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the index head in asemiconductor device test handler of the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An index head assembly for a semiconductor device test handler,comprising: a carrier base configured to be fixed to a transfer deviceof the handler; an elevating carrier movably coupled to the carrier baseand configured to be raised and lowered relative to the carrier base; anelevating device configured to raise and to lower the elevating carrierrelative to the carrier base; a head holder movably coupled to a lowerportion of the elevating carrier via at least one guide member andconfigured to move in a vertical direction relative to the elevatingcarrier; and a plurality of heads fixed to the head holder, wherein eachof the plurality of heads comprises: a holding part configured to hold asemiconductor device with a vacuum force; a heating part positioned onan upper portion of the holding part and configured to generate and totransfer heat directly to the semiconductor device when thesemiconductor device is mounted in a test socket of the handler; and acompliance part positioned on an upper portion of the heating part andconfigured to properly align the semiconductor device held by theholding part and the test socket.
 2. The index head assembly as claimedin claim 1, further comprising a force transducer positioned between theelevating carrier and the head holder and configured to measure a loadapplied by the elevating carrier based on a displacement of theelevating carrier with respect to the head holder when the semiconductordevice mounted in the test socket is pressed down.
 3. The index headassembly as claimed in claim 2, wherein the force transducer comprises aload cell.
 4. The index head assembly as claimed in claim 1, wherein theat least one guide member comprises guide pins positioned on oppositeend portions of an upper portion of the head holder and configured to beinserted into corresponding holes in the elevating carrier so as toallow the head holder be movable in a vertical direction relative to theelevating carrier.
 5. The index head assembly as claimed in claim 1,wherein the at least one guide member comprises a pair of linear motion(LM) guides fitted to the elevating carrier in so as to be oriented in avertical direction, and a corresponding pair of LM blocks fixed to arear surface of the head holder and coupled to the pair of LM guides. 6.The index head assembly as claimed in claim 1, wherein the compliancepart comprises: an upper block fixed to the head holder and comprising aplurality of holes formed in a lower portion thereof; a plurality ofball plungers each comprising an elastic body configured to be insertedinto and retained in a corresponding hole of the plurality of holesformed in the upper block, a retainer coupled to a lower end of theelastic body, and a ball configured to be retained under the retainersuch that a portion of the ball is exposed at a bottom surface of theupper block; a lower block configured to be coupled to a bottom portionof the upper block with a preset allowance thereberween; and a pluralityof recesses formed in an upper surface of the lower block at positionscorresponding to the holes formed in the upper block , wherein theplurality of recesses are configured to receive and to hold the balls ofthe plurality of ball plungers.
 7. The index head assembly as claimed inclaim 1, wherein the heating part comprises: a heating block formed of aconductive material and comprising a heater configured to generate andto transfer heat to the holding part; a through hole formed in a centralportion of the heating block; and a coupling nozzle coupled to thecompliance part with a space formed therebetween, wherein the couplingnozzle is configured to be inserted into and fixed in the through holeso as to form a vacuum therein.
 8. The index head assembly as claimed inclaim 7, wherein a lower end of the coupling nozzle is configured to beflexible.
 9. The index head assembly as claimed in claim 8, wherein alower end of the coupling nozzle is formed of an elastic material. 10.The index head assembly as claimed in claim 9, wherein a lower end ofthe coupling nozzle is formed of silicone.
 11. The index head assemblyas claimed in claim 7, wherein the holding part comprises: a pocketblock formed of a conductive material and configured to closely contacta bottom surface of the heating block; a through hole formed in a centerportion of the pocket block; a floating nozzle configured to be insertedinto and coupled to the through hole, and to be connected to thecoupling nozzle so as to absorb and to hold the semiconductor devicewith a vacuum force; and a plurality of blades formed of anon-conductive material and positioned vertical to a bottom surface ofthe pocket block, wherein the plurality of blades are configured topress on leads of the semiconductor device so as to bring the leads intocontact with a terminal part of the test socket.
 12. The index headassembly as claimed in claim 7, wherein the heater comprises an electricheater.
 13. The index head assembly as claimed in claim 1, wherein theholding part comprises: a pocket block formed of a conductive materialand configured to closely contact a lower surface of the heating part; athrough hole formed in a center portion of the pocket block; a floatingnozzle configured to be inserted into and coupled to the through hole,and to be connected to the heating part so as to absorb and to hold thesemiconductor device with a vacuum force; and a plurality of bladesformed of a non-conductive material and positioned so as to be orientedin a vertical direction relative to a bottom surface of the pocketblock, wherein the plurality of blades are configured to press on leadsof the semiconductor device so as to bring the leads into contact with aterminal part of the test socket.
 14. The index head assembly as claimedin claim 13, wherein the floating nozzle is configured to be movablycoupled to the through hole so as to allow vertical movement of thefloating nozzle through a preset distance.
 15. The index head assemblyas claimed in claim 14, wherein the through hole comprises steps formedat an upper part and a lower part of the through hole each withdiameters greater than an intermediate part of the through hole, andwherein the floating nozzle comprises rims extending outward from anupper part and a lower part of the floating nozzle and configured toengage with the steps so as to limit vertical movement of the floatingnozzle in the through hole.
 16. The index head assembly as claimed inclaim 13, wherein the heating part comprises a heating block, andwherein the pocket block is configured to closely contact a bottomsurface of the heating block.
 17. The index head assembly as claimed inclaim 13, wherein the heating part comprises a coupling nozzle, andwherein the floating nozzle is configured to be coupled to the couplingnozzle.
 18. The index head assembly as claimed in claim 1, furthercomprising a plurality of positioning holes formed in the holding partof the head and configured to receive a plurality of positioning pinspositioned proximate the test socket.
 19. The index head assembly asclaimed in claim 18, wherein the plurality of positioning holes areconfigured to mate with the plurality of positioning pins to accuratelyguide a head of the plurality of heads onto a corresponding test socketof the handler.
 20. The index head assembly as claimed in claim 1,wherein the elevating device comprises: a linear motion (LM) guide fixedto the carrier base; a LM block fixed to the elevating carrier andcoupled to the LM guide; a ball screw fixed to the carrier base andcoupled to the elevating carrier; and a motor configured to drive theball screw.
 21. The index head assembly as claimed in claim 1, whereinthe compliance part is configured to provide a plurality of degrees offreedom to the plurality of heads so as to properly align thesemiconductor device in the test socket.